选择查询中出现更新错误的SQL Server查询

错误是：

子查询返回了多个值。当子查询在=、！=、=或者当子查询用作表达式时

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我想你需要这样的东西：

update ItinventoryR1 
set iin_userid = (select emp.empid 
                  from employee emp, itinventoryr1 it 
                  where ltrim(rtrim(it.iin_username)) in (emp.empname))

联接表，并更新其中一个表

试试这个

UPDATE R1
SET iin_userid = emp.empid
FROM itinventoryr1 R1
INNER JOIN employee emp
    ON ltrim(rtrim(R1.iin_username)) = emp.empname

update t1 
set t1.iin_userid =t2.emp_id
from ItinventoryR1 as t1 inner join employee emp as t2
on ltrim(rtrim(t1.iin_username))=t2.empname